fuel pump wiring help needed.....

[87Limited2Turbo]

the pigtail for my fuel pump and sending unit were cut by some idiot before i got it. the tank is going into my 87 Limited. i have decided (for money reasons) that im not gonna swap the tail light harness for the moment and was wondering if someone could help me by sketching out a wiring diagram to wire up the pump and sending unit so that i wont have any problems. i know it needs a relay. a "friend" suggested just hooking it up direct with a switch but i know that isnt good on the pump. before i realized that money was gonna run short on this project i got a great deal on a new hotwire kit so i grabbed it. i dont mind cutting the plugs off of it to wire up my pump, but not sure how being i dont have the tail light harness that it gets power from and want to be sure its right. i know it still needs power to initiate the relay, but dont wanna do it wrong and cost myself more money that isnt needed. the only instructions i can find are on gnttype.org and it details it with the correct rear harness.

so if anyone has the time to draw me out something to help i would really appreciate it. later when money permits i intend to swap the harness and do it and other things correctly but need a reliable/safe fix til then.

 

[DailyDrifter]

I'll try and type this out as easy as possible. The gray wire coming from your sending unit it the power for the pump. Get 10 gauge wire and crimp an ring terminal (Goes on the back of the alt) on one end, and run it back to the fuel pump. Get a relay with 4 pins, 2 pins will be used to trigger the fuel pump, and the other 2 will be for the fuel pump itself. Take the triggering part of the relay and ground 1 of the pins, the other pin will go to the stock fuel pump wire on the body (not sure of the color) once the key it turned on it will trigger the relay. Next connect the 10 gauge wire (from alt) to the relay and then connect the fuelpump wire (from the sending unit) to the relay using another little peice of 10 gauge wire. That should be it :wink:, I think Gnttype.org has instructions.


BTW your "friend's" idea would work but you would probably burnt he switch up pretty fast. If I remember i'll take a picture of a hotwire kit I did the other day where the factory wires were cut and a relay was put in there.

 

[Sam Colalillo]

This illustration shows the factory harness which plugs into the fuel pump sending unit socket assembly. The tan wire with the white tracer connects to the gray power wire Daily Drifter is referring to. (Tan with a white tracer connects to the gray fuel pump power supply wire). There are three wires at this connection. The other two are: Ground wire, and the rheostat power for the fuel level gauge.


The other portion of this diagram shows the ECM Terminal A1. The ECM has an internal relay which triggers power to terminal A1 of the ECM for the fuel pump to come on. This wire goes out to the center relay on the passenger side fender (fuel pump relay).


This is how I would hot wire it. Constant power would be from the power supply stud on the back of the alternator.